This invention relates to a hinge assembly used, for example, in a one-touch operation type cellular telephone and capable of turning a reception section of the cellular telephone from a closed position to an open position by one-touch operation.
Heretofore, there has been known a foldable cellular telephone in which a reception section located in a closed position can be turned into an open position by one-touch operation. Normally, a foldable cellular telephone of this type includes a hinge assembly for turnably connecting a transmission section and a reception section together, a locking mechanism for non-turnably locking the transmission section and the reception section in the closed position and an unlocking mechanism for releasing a locked state achieved by the locking mechanism. When the locked state achieved by the locking mechanism is released by the unlocking mechanism, turn biasing means disposed at the hinge assembly biases the reception section so as to be turned from the closed position to the open position with respect to the transmission section (see Japanese Patent Application Laid-Open No. H08-298538 and Japanese Patent Application Laid-Open No. H11-41328).
In the above-mentioned conventional cellular telephone, the hinge assembly and the locking mechanism are separately provided. Accordingly, it has such problems that manufacturing costs for those separately provided component parts are increased and the number of processes for assembling those component parts to the cellular telephone is increased. Moreover, the conventional locking mechanism has the following problem. Since the reception section is prevented from turning as long as the locked state is released, any undue attempt to turn the reception section from the closed position towards the open position side results in destruction of the locking mechanism.
In order to achieve the above problems, the features of the present invention reside in a hinge assembly comprising a hinge shaft for turnably connecting two articles about a rotation axis between a closed position and an open position, a first hinge member disposed at one of the two articles such that the first hinge member is non-turnable and non-movable in the direction of the rotation axis, a second hinge member placed opposite the first hinge member in the direction of the rotation axis and disposed at the other article such that the second hinge member is non-turnable but movable in the direction of the rotation axis, turn biasing means disposed between the two articles and for turn biasing the two articles from the closed position side towards the open position side, a locking mechanism for non-turnably locking the first and second hinge members so that the two articles are located in the closed position, and a lock releasing mechanism for releasing the locked states of the first and second hinge members caused by the locking mechanism and allowing turning of the first and second hinge members, wherein the locking mechanism includes a plurality of engagement members disposed between the first hinge member and the second hinge member in such a manner as to be away from each other in the circumferential direction about the rotation axis, and direct acting biasing means for biasing the second hinge member towards the first hinge member side along the rotation axis and pressing the second hinge member against the first hinge member through the engagement members, the first hinge member is provided with a guide portion for connecting the engagement members to the first hinge member such that the engagement members are non-turnable but movable in the radial direction, and the second hinge member is provided with a locking portion which is raised towards the first hinge member side and which is varied in height along the radial direction about the rotation axis, the engagement members being locked by a high part of the locking portion, thereby preventing the first and second hinge members from turning from the closed position towards the open position side, and wherein the lock releasing mechanism includes a control member which is externally controllable between a first position and a second position, and movement means for moving the engagement members from a high side towards a low side of the locking portion in accordance with movement of the control member from the first position towards the second position side, the engagement members being able to override the locking wall portion on the low side of the locking portion by biasing force of the turn biasing means.
It is preferred that each of the engagement members is formed of a spherical body.
It is also preferred that the guide portion is formed as a slot extending on a radial line orthogonal to the rotation axis, and the engagement members are received in the slot such that the engagement members are non-movable in the short direction of the slot but movable in the longitudinal direction.
Moreover, it is preferred that the thickness of the first hinge member in the direction of the rotation axis at least at that area where the slot is formed, is smaller than the length of the engagement member in the direction of the rotation axis, one part of the engagement member projects from the slot towards the second hinge member side and the other part of the engagement member projects from the slot towards the opposite side, the movement mean includes a cam member disposed at the opposite side of the second hinge member with respect to the first hinge member and turned about the rotation axis by movement of the control member from the first position to the second position, the cam member has a driving recess formed in an opposing surface thereof with respect to the first hinge member, the driving recess being slanted with respect to the radial line of the first hinge member and co-acted with the slot to move the engagement member from the high part side towards the low part side of the locking wall portion at the time of turning of the cam member.